The gently rising sun cast just enough light and shadow to create confusion. Two nights earlier, the first snowfall of the season had blanketed the region in a thick, soft white shroud; one night later, fierce winds had blown much of that away, leaving only patches off which the low light ricocheted blindingly.

Every pale patch on the ground was a polar bear hunched in the willows, sheltering from the wind. Until it wasn't: Upon closer inspection, each suspect reverted to being snow, a rock, a trick of the light.

I was a guest on Buggy One, a kind of mobile research station on monster truck wheels (a stripped-down version of the buggies used for tourists); next to me, a small group of American scientists sat abreast, looking into a camera that was streaming video live to classrooms in Kentucky and Oregon, where schoolchildren were gathering for a virtual question-and-answer session.

How far can polar bears swim? How do they hold onto the ice? How long do they live? How big do they get? Are they endangered?

"Perhaps we'll see one walk past," one of the researchers had suggested, somewhat optimistically, at the beginning of the teleconference. But although there was no polar bear in the view of the camera, off to the side, among the willows, my eye caught movement. I looked again. This was no optical illusion. A polar bear was ambling, ever so slowly, in our direction.

It was moving as polar bears do: seemingly aimlessly, languorously, its head and neck occasionally swaying loosely and slowly from side to side. I put my camera to my eye, but even at the fullest extent of my telephoto lens, the bear was little more than a small white blob, barely large enough to occupy the very center of my picture frame. Whispering to myself, I urged it forward as it wandered toward us.

But however relaxed a polar bear's stride may be, it can effortlessly eat a great deal of distance in a surprisingly short space of time, and by the time I had bundled up and slipped out onto the buggy's rear deck, the bear was no more than 30, 40 yards away, casually looking up at me as it advanced. Like a ghost, its approach was silent until, suddenly it was so close that its head and then just its snow-dappled muzzle filled my viewfinder. I lowered the camera and looked the animal in the eye as it looked up at me.

Only now, with the bear perhaps two or three yards below my elevated position, did I finally hear an almost imperceptible noise: a soft crunch of snow beneath its massive paws. The bear paused and considered me. Then it huffed out a short breath and padded past the buggy and across the tundra, never looking back.

***

Ten years earlier, on an icebreaker in the Russian and Alaskan Arctic, I had marveled at polar bears that watched us nonchalantly from the ice floes. Their shoulders rolled as they swaggered like professional prizefighters.

"Oh, yeah," said one of the deckhands admiringly as we gazed at one seemingly self-confident specimen. "Look at him. He owns the ice."